Quote #3

Now I wish to introduce the following idea. Between the age limits of nine and fourteen there occur maidens who, to certain bewitched travelers, twice or many times older than they, reveal their true nature which is not human, but nymphic (that is, demoniac); and these chosen creatures I propose to designate as "nymphets." (1.5.5)

Humbert's definition of nymphet is very precise. He wants to make sure that the reader knows exactly the kind of girl he adores. Why is this information so important to him? Isn't it incriminating?